How would this apply to a Blessed as they do not have power points? Can they simply lay on hands until the wounds are all healed or is there a rules limit to this use that I cannot find?

There is no absolute limit on the number of times a Blessed can use the Healing power, but there is a functional "limit" based simply on the rules they use.

The Blessed suffers a -2 for the Rank of the power, and even if offset with Conviction, then they also suffer a penalty equal to the wounds of the target from -1 to -3. If they fail, then they gain a level of Fatigue for an additional -1 to try again, making it more likely they fail again. If they fail three times, they are Incapacitated for 3 hours, which means the Golden Hour is over.

And that doesn't even touch on any of those rolls coming up a 1 on the Faith die causing a Crisis of Faith._________________Clint Black
Savage Worlds Core Rules Brand Manager